Advanced Light Microscopy

Volume 2 Specialized Methods

Maksymilian Pluta Professor of Applied Optics Head of the Physical Optics Department Central Optical Laboratory, Warszawa

Elsevier Amsterdam-Oxford-New York-Tokyo PWN-Polish Scientific Publishers Warszawa 1989 Contents

Introduction, XI Chapter 5. Phase Contrast Microscopy, 1 5.1. General principles, 1 5.2. Typical phase contrast systems, 11 5.3. Imaging properties, 15 5.3.1. Halo, shading-off, and image fidelity, 15 5.3.2. Resolution, 20 5.3.3. Sensitivity, 22 5.3.4. Influence of stray light, 25 5.4. Nomenclature, 28 5.5. Highly sensitive phase contrast devices, 30 5.5.1. Optical properties of soot layers, 30 5.5.2. Highly sensitive negative phase contrast device (KFA), 32 5.5.3. Highly sensitive positive phase contrast device (KFS), 36 5.6. Alternating phase contrast systems, 38

5.6.1. Beyer's phase contrast device, 39 v 5.6.2. Device with both positive and negative phase rings (KFZ), 42 5.7. Phase contrast systems with continuously variable image contrast, 45 5.7.1. The Polanret system, 46 5.7.2. Nomarski's variable achromatic phase contrast system, 50 5.7.3. Nikon interference-phase contrast device, 52 5.7.4. Variable phase contrast device with a single polarizing phase ring, 54 5.8. Phase contrast microscopy by using interference systems, 56 5.8.1. Interphako, 57 5.8.2. Variable phase contrast microscopy based on the Michelson inter­ ferometer, 61 5.9. Stereoscopic phase contrast microscope, 66 5.9.1. Underlying principles and mode of operation, 67 VI CONTENTS

5.9.2. Lateral resolution, 70 5.9.3. Stereoscopic axial resolution, 73 5.10. Phase contrast for incident light, 74 5.10.1. System with phase plate immediately behind the beam-split­ ter, 74 5.10.2. Incident-light phase contrast microscope with internal projection system, 76 5.10.3. System with phase plate in objectives, 77 5.11. How and where to use the phase contrast microscope, 78 5.11.1. Adjustment of phase contrast microscopes, 79 5.11.2. General remarks on specimens for phase contrast micro­ scopy, 81 5.11.3. Phase contrast microrefractometry, 85 5.11.4. Fields of application of phase contrast microscopy, 88

Chapter 6. Amplitude Contrast, Dark-Field, Optical Staining, Modulation Con­ trast, and Other Related Techniques, 91 6.1. Amplitude contrast technique, 91 6.1.1. Theoretical considerations, 91 6.1.2. Practical implementation and properties, 96 6.2. Oblique illumination, dark-field microscopy, and related techniques, 100 6.2.1. Oblique illumination, 101 6.2.2. Oblique dark-field illumination, 102 6.2.3. Dark-field microscopy with detuned interference filters, 108 6.2.4. Central dark-field microscopy, 110 6.2.5. Microstrioscopy, 111 6.2.6. Ultramicroscopy, 112 6.3. Optical staining, 113 6.3.1. Rheinberg illumination, 113 6.3.2. Double illumination, 115 6.3.3. Dispersion staining, 117 6.3.4. Other optically stained images, 132 6.4. Modulation contrast microscopy, 134 6.4.1. Theoretical principles, 134 6.4.2. Practical implementation, 138 6.4.3. Properties and applications, 141 6.5. Monoobjective stereoscopic microscopy, 142 CONTENTS VII

Chapter 7. Differential Interference Contrast, 146 7.1. Background and principles of DIC microscopy, 146 7.1.1. On the typical use of the Mach-Zehnder interferometer, 148 7.1.2. Mach-Zehnder interference system used as a wavefront shear inter­ ferometer, 151 7.1.3. DIC microscopy as a method for displaying optical gradients, 153 7.1.4. DIC microscopy based on the double refracting interference system, 156 7.2. Nomarski DIC microscopy, 165 7.2.1. Nomarski DIC system for transmitted light, 165 7.2.2. Amplitude DIC microscopy, 174 7.2.3. The image of a light point in the Nomarski DIC microscopy, 175 7.2.4. Nomarski DIC system for reflected light, 177 7.3. Video-enhanced DIC microscopy, 181 7.4. Differential interference contrast microscopy with continuously variable wavefront shear, 183 7.4.1. Transmitted-light VADIC system with pupilar compensation, 183 7.4.2. Transillumination VADIC system with condenser slit dia­ phragm, 189 7.4.3. VADIC system for reflected light, 192 7.5. A DIC microscope for testing cross-sections of optical fibres, 196

Chapter 8. Reflection Contrast Microscopy, 198 8.1. Optical principles of RC microscopy, 198 8.1.1. Light reflection and interference in RC image formation, 198 8.1.2. Discrimination between pure reflection and interference, 202 8.1.3. Evaluation of the RC image by measurement of reflectivity, 203 8.2. Instrumentation of RC microscopy, 204 8.2.1. Leitz-Ploem RC microscopy, 204 8.2.2. Other systems for RC microscopy, 207 8.3. Applications of RC microscopy, 208

Chapter 9. Fluorescence Microscopy, 211 9.1. General principles and types of fluorescence microscopy, 212 9.2. Immunofluorescence microscopy, 216 9.3. Instrumentation of fluorescence microscopy, 222 9.3.1. Light sources for fluorescence excitation, 222 VIII CONTENTS

9.3.2. Exciter and barrier filters, 228 9.3.3. Dichroic mirrors, 238 9.3.4. Objectives and condensers for fluorescence microscopy, 240 9.3.5. Ploemopak epi-illuminator, 242 9.3.6. Other devices and facilities, 246 9.4. Fluorescence combined with other microscopical techniques, 248 9.5. Laser fluorescence microscopy, 252 9.6. Total internal reflection fluorescence microscopy, 256 9.7. Surgical fluorescence microscopy, 257 9.8. Fields of application of fluorescence microscopy, 262 9.8.1. Application in biology and medicine, 262 9.8.2. Application in materials sciences, 263

Chapter 10. Ultraviolet and Infrared Microscopy, 264 10.1. Observation of UV and IR images, 264 10.2. UV microscopy and its applications, 268 10.3. IR microscopy and its applications, 272 10.4. Thermal microscopy, 278

Chapter 11. Holographic Microscopy, 282 11.1. A bird's eye view of the history of holographic microscopy, 283 11.2. Principles of holographic microscopy, 285 11.2.1. Recording of typical holograms of transparent objects, 286 11.2.2. Holographic image reconstruction, 289 11.2.3. Holography of light-reflecting objects, 292 11.2.4. Classification of holograms, 295 11.3. Holographic microscopy without objective lenses, 296 11.3.1. In-line microholographic system, 296 11.3.2. Off-axis microholographic system, 300 11.3.3. Other lensless holographic systems for microscopy, 301 11.4. Holographic microscopy combined with objective lenses, 302 11.4.1. Microholographic systems with premagnification and direct wave- front reconstruction, 302 11.4.2. Holographic microscopy with premagnification and reversed wavefront reconstruction, 308 11.4.3. Other lens-assisted holographic systems for microscopy, 311 11.5. Problems of coherent noise elimination from holographic micro­ scopy, 312 CONTENTS IX

11.5.1. Coherent noise and speckle patterns, 312 11.5.2. Techniques for coherent noise reduction, 314 11.5.3. Holographic microscopy with unidirectional suppression of co­ herent noise, 317 11.6. Holographic interference microscopy, 325 11.6.1. Advantages of holographic interference microscopy, 326 11.6.2. Real-time holographic interference methods, 329 11.6.3. Double-exposure holographic interference microscopy, 332 11.6.4. It is possible to accept holographic interference microscopy with­ out coherent noise reduction? 335 11.7. Holographic phase contrast microscopy, 336 11.8. Applications of holographic microscopy, 337 11.8.1. Examples of biological applications, 338 11.8.2. Applications in materials sciences, 339 11.8.3. Holographic imaging and analysis of three-dimensional distribu­ tion of particles, 340 Chapter 12. Laser Projection, Scanning, and Other New Microscope Sys­ tems, 353 12.1. Laser projection microscope with brightness amplifier, 353 12.2. Scanning optical microscopy, 355 12.2.1. Confocal scanning microscopy, 356 12.2.2. Laser-scan microscope developed by С Zeiss Oberkochen, 363 12.2.3. Tandem scanning reflected-light microscope, 365 12.2.4. Other scanning light microscopes, 368 12.3. Nonlinear microscopy with second harmonic generation, 371 12.4. Raman microscopy, 373 12.5. Optoacoustic and photothermal microscopy, 375 Epilogue to Volume 2, 380 References, 384 Index of Names, 421 Subject Index, 424 Plates, 447